The present invention relates to coiling machines, although other uses will be apparent from the teachings disclosed herein. In particular, the present invention relates to coiled spring assemblies produced in a unified process. A specific embodiment of the coiled spring assemblies includes coiled ferrite spring assemblies which are of particular use in the automotive industry for reduction of electromagnetic interference (EMI) during ignition system firing.
Spring coiling machines are well known in the art. Spring coiling machines and methods are discussed in U.S. Pat. No. 5,036,690, entitled "Flexible Pipe End Crimping Apparatus," issued Aug. 6, 1991; U.S. Pat. No. 5,452,598, entitled "Automatic Spring Formation Apparatus," issued Sep. 26, 1995; and U.S. Pat. No. 5,791,184, entitled "Spring-Making Machine," issued Aug. 11, 1998. U.S. Pat. No. 5,036,690; 5,452,598; and 5,791,184 are incorporated herein, in their entirety, by reference. It is also known in the art to provide inserts in springs.
It has, however, been difficult to manufacture spring assemblies with plugs in a single continuous or unified process. Generally, the insert might be maintained in place by crimping the coils around the insert or inserting wire or flat stock about the ends of the coil to hold down the insert within the coil. These and other prior art methods for producing coiled plugs usually require inserting the plug into the coil after the coil is produced as a finished product. For example, the spring is manufactured, then in a separate process the cylinder is inserted into the spring (typically "by hand"). And then, in another separate process, the cylinder is secured in the spring by one of the aforementioned methods. These prior art methods involve multiple separate steps, often done by hand, and as a result have reliability and efficiency problems associated with them.
The present invention overcomes these problems and provides advantages heretofore unattainable.